Although the weight-loss surgery has been shown to decrease weight and diminish diabetes, the older, severely obese male patients in the study were not living longer because of the procedure.

The study was to be presented Sunday at the Academy Health Annual Research Meeting.

For the severely obese, bariatric surgery is one of the most effective ways to reduce weight. The most common bariatric surgery is gastric bypass, which creates a small stomach pouch that restricts food intake.

The study conducted at Veteran Affairs medical centers followed 850 veterans who had bariatric surgery from January 2000 to December 2006.

When study authors compared the raw rates, patients who had surgery had lower mortality rates with 6.8 percent versus 15.2 percent after six years.

But when researchers compared the 850 veterans to 1,694 similar patients who did not have bariatric surgery, they found that surgery was not significantly associated with reducing mortality.

Matthew Maciejewski, of Durham VA Medical Center and colleagues concluded that “bariatric surgery does not appear to be associated with survival during a mean of 6.7 years of follow-up.”